A camera calibration is defined as to find out an intrinsic construction (for example, lens property and imaging method) and an extrinsic construction (for example, position and direction of a camera). It is a major technical issue in a field of computer vision, and also an augmented reality-based core element technology whose interest is increased recently.
Information on a camera intrinsic construction is not explicitly known if not an expensive one, and it is not easy to measure information on a camera extrinsic construction except a special case. Accordingly, a variety of methods to measure such intrinsic and extrinsic construction information are suggested, which usually use a single image for three-dimensional object constructed precisely in advance or a plurality of images for a checkerboard whose size is known.
However, the three-dimensional object is so complicated that it is not easy to use it in a normal environment and that it is not proper to apply to a cheap camera such as a smart phone camera. While a method to use a plurality of images for a simple checkerboard is most widely used, such a method takes a long time comparatively to measure so that it is not easy to apply to a real time application.